Diamond-Covered Substrate, Filter And Electrode

a technology of diamond layer and substrate, applied in the direction of electrode coating, separation process, instruments, etc., can solve the problems of deterioration of diamond layer, serious efficiency loss, and easy corrosion of conventional ceramic filters, and achieve low resistance of diamond layer, improve power efficiency, and improve the effect of resistance valu

Inactive Publication Date: 2008-01-17
SUMITOMO ELECTRIC IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0011] A further object of the invention is to provide a physically and chemically remarkably stable porous composite substrate having excellent durability and capable of being used in severe environments, by providing an electroconductive diamond covering layer on a porous substrate having open pores and having a filtration function.
[0034] The present invention is a diamond-covered substrate which has a filtration function and is also capable of being used as an electrode. This exhibits an effect that delamination between the electroconductive diamond layer and the substrate is prevented even during an electrochemical oxidation treatment process by preventing corrosion of the substrate itself and reducing stresses in the diamond layer.

Problems solved by technology

However, conventional ceramic filters are prone to corrosion when used in extremely corroding solutions and / or environments.
These electrodes may also corrode during electrolysis processes when placed in chemically severe environments.
Such electrodes are also problematic when used as anode, in that adsorbates form on the electrode working surface, which causes a serious efficiency loss.
However, the examples described in these specifications do not illustrate an example of electrolysis at high current densities and over long time.
This delamination causes the underlying substrate to be exposed, thereby corrosion proceeds by the solution.
Alternatively, severely impaired electrolysis efficiency poses another problem.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0037] A film of electroconductive diamond layer was formed by use of the substrates listed in Table 1. The substrate used here had an open pore diameter of about 1 μm. As a pretreatment, it was subjected to a scratching treatment with diamond powder, or an ultrasound treatment in a solution containing diamond powder dispersed therein. The size of the diamond powder varied from 0.2 μm to 3.0 μm.

[0038] Synthesis by hot filament CVD was carried out under a gas pressure of 60 Torr, hydrogen flow of 3,000 sccm, and a methane flow of 0.5 to 5.0 sccm. The boron source was diborane gas. The diborane flow was supplied at a concentration of 0.2 to 1.0% with respect to methane. The temperature of the substrate was 700 to 1,000° C. In the case of microwave CVD, the microwave frequency was 2.4 GHz, and the microwave output was 5 kW. In all cases the boron was contained in the range of from 10 ppm to 10,000 ppm.

[0039] As displayed in Table 1, nucleation density was changed by modifying the met...

example 2

[0041] An electroconductive diamond film was formed on the porous substrates in which the open pore diameter varied as illustrated in Table 2. Using the produced diamond-covered substrates, a solution was circulated through the substrate by a pump that fed the solution from one side of the substrate towards the opposite side. As the solution, a mixture of a sludge-like precipitate including diamond powder and a mixed organic solution of trichloroethylene and acetone, was mixed into a 0.1 M aqueous solution of sulfuric acid, then it was used. An electrochemical oxidation treatment was carried out simultaneously while this solution was filtered. Filtration of the solution proceeded for 4 hours through recirculation of the solution.

TABLE 2SubstrateOpen poreNo.materialdiameter (μm)Test result2-1Nb0.09No solutionpassage2-2Nb0.11Filtrationpossible2-3Nb999Filtrationpossible2-4Nb1001Substratebreakage

[0042] No. 2-1, which had a largest open pore diameter smaller than 0.1 μm, the porous sub...

example 3

[0043] An electroconductive diamond film was formed on a porous substrate by use of the substrate materials varied as shown in Table 3. An electrochemical oxidation treatment was carried out in the same way as in Example 1. × denotes substrates that suffered corrosion during the treatment, while ◯ denotes substrates where no corrosion occurred. The electrochemical oxidation treatment was prolonged a further 100 hours with a current density of 1.5 A / cm2 (electrolysis treatment 2). × denotes the substrates suffering delamination between the substrate and the diamond film, while ◯ denotes the substrates where no such delamination occurred.

TABLE 3Electrolysistreatment 2SubstrateSubstrateFilmNo.materialcorrosiondelamination3-1Al∘x3-2Ta∘x3-3Nb∘∘3-4Hf∘x3-5Zr∘x3-6Zn∘x3-7Mox—3-8Cux—

[0044] As for the substrate materials in Nos. 3-1 to 3-6, the electrochemical oxidation treatment could proceed stably. Other than them, Nos. 3-7 and 3-8 suffered corrosion at portions where the substrate was no...

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Abstract

By providing a substrate that can be used as an electrode, the invention solves the problem of corrosion of the substrate itself during an electrochemical oxidation treatment, the problem of discontinued electrolysis caused by delamination between a diamond layer and a substrate, or the problem of severely impaired electrolysis efficiency. The present invention is a diamond-covered substrate comprising a substrate and a conductive diamond layer covering the substrate, wherein the largest area of the portion where the diamond comprising the diamond layer is continuous ranges from 1 μm2 to 1,000 μm2. Preferably, the substrate is porous and has open pores, and the open pores preferably have a diameter from 0.1 μm to 1,000 μm.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite substrate in which a porous substrate is covered with a diamond layer, and to a filter and an electrode using the composite substrate. BACKGROUND ART [0002] Diamond has characteristic properties then numerous products in many applications put into practical use by exploiting them. Diamond is physically and chemically stable, and is ordinarily an insulating material. Diamond can be electroconductive, however, by addition of impurities such as boron, nitrogen and the like. [0003] Technologies for material disposal, effluent handling and recycling in industry have been all developed rapidly in recent years. One such technology is effluent filtration using ceramic filters. However, conventional ceramic filters are prone to corrosion when used in extremely corroding solutions and / or environments. [0004] Electrochemical oxidation treatment technologies have also been known in order to reduce unwanted organic compounds in ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B9/04
CPCB01D39/04B01D39/2051B01D39/2093B01D2239/0241B01D2239/0478B01D2239/1216Y10T428/24802C02F2001/46138C23C16/271C23C16/274C23C16/278C25B11/03C25B11/0447C02F1/46109C25B11/075C23C16/27C25B11/04
Inventor IZUMI, KENJISEKI, YUICHIROIMAI, TAKAHIRO
Owner SUMITOMO ELECTRIC IND LTD
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